Normal adult color vision depends upon the presence of three different cone types in the retina, plus additive and subtractive recombinations of the receptor signals into a more central color code. The spectral sensitivities of the different cone types, and the recombination rules, are typically studied in adults by means of behavioral (psychophysical) testing techniques. Our goal is to elucidate the development color vision in infants. Behavioral techniques known as forced-choice preferential looking (FPL) will be used with infants 1 to 3 months of age. Two lines of studies will be carried out. First, the technique of chromatic adaptation (Stiles' two-color threshold technique) will be used to isolate each of the three cone types in turn, and study its spectral response characteristics. Second, several paradigms which, in adults, reveal major interactions between cone types (including "Sloan notched", test additivity, and field additivity) will be used to explore the development of postreceptoral channels. Potentially color-blind as well as presumptively color-normal infants will be studied.